Across 1,000 years of traceable history, Ashkenazi Jews have ridden countless waves of success and hardship. This may partly explain the sober reflection that followed last week's news that yet another cancer-causing gene runs through Jewish families with roots in Eastern Europe.

Researchers at Johns Hopkins Oncology Center announced that they had identified a genetic defect shared by about 700,000 Jews that predisposes them to colorectal cancer. The news had a familiar ring: Just a few years ago, scientists found that Ashkenazi women are at risk for two mutations that trigger breast cancer.

Surely, the latest news was received in some quarters with the age-old question, "Why the Jews?"

But some had a different perspective.

"I'm a Jew of Eastern European descent, so I can speak only for myself -- it's a constant concern, but so are taxes," said George Berlin, a history professor at the Baltimore Hebrew University. "We're not different than any other group where a predisposition has been found to a particular illness."

Within three days of the Aug. 25 announcement, 250 people called a Hopkins hot line (410-955-4041) to ask about a blood test that is being offered to Ashkenazi Jews who have a family history of colon cancer. Hopkins opened a second phone line to handle the deluge.

Callers came largely from Baltimore's large Jewish community but also from cities across the

country.

"No one has been hysterical," said Marijayne Bushey, a research assistant who has handled many of the requests. "Everyone who calls is at the very least interested, at most concerned. Everyone's just happy to have whatever information we can provide at this time."

Test recommendation

Scientists who made the discovery are recommending the test for adult Jews of Eastern European descent who know of at least one relative who had colon cancer. People who test positive for the gene can use the information to get examined early -- and often -- for signs of suspicious growths in their colon.

Surgery can cure many patients, but only if the disease is caught early.

When she heard the news, Laurie Kramer of Baltimore remembered an uncle once treated for a precancerous polyp.

"As an Ashkenazi Jew, when I found out there is this test for a disease which can be prevented -- that, to me, said I should probably get tested," said Kramer, 37. "There are some genetic diseases like Huntington's disease where, if you find out you have it, there is absolutely nothing you can do about it."

Kramer works at a Hopkins medical unit, writing software for a computer database that serves as a worldwide clearinghouse for information about the human genome, the set of genes that is unique to humans. Although she is comfortable with genetic principles, she is worried that insurance companies might use genetic information to discriminate against people.

"I think it's a very big issue that the country has to grapple with," she said.

The Ashkenazim can be traced to the 10th century -- to the towns and cities of Germany where Jews were forced to live in designated sections.

They seldom socialized with non-Jews and hardly ever married outside their community.

"Typically, the only contact they would have with the non-Jewish community would be in business matters," Berlin said.

Beginning in the 13th century, "a variety of expulsions over the course of centuries" caused groups to migrate to Poland and, later, Russia. They formed the nucleus of the vibrant culture that now is associated with Eastern European Jewry but had its roots -- genetic and otherwise -- in Germany.

Dr. Bert Vogelstein, the world-famous cancer researcher who helped identify the gene, said it is not surprising that science has turned up a few harmful genes that run through Jewish families. Vogelstein said such genes can cluster in any ethnic group that is relatively small and has spent many years in geographic isolation.

Passed along

The phenomenon is known as the "founder's effect." Somehow, a mutation occurs in a particular person and gets passed to future generations. The gene remains confined to the ethnic group because its members marry among themselves.

When the mutation "starts with a small number of individuals, then it becomes genetically isolated over time," Vogelstein said. "Just by chance, some mutations will increase in frequency, some will decrease."

In the case of Jews, persecution also may have played a role.

Over the centuries, periods of high growth in Europe's Jewish population were often followed by massacres. "You have this tremendous population decimation, then the next wave of population growth is going to start with a relative handful of people," said Gloria Peterson, a cancer epidemiologist who worked on the Hopkins study.

This caused "population bottlenecks" through which deleterious genes could pass by chance, remaining confined to a relative few.